1. Field of the Invention
This invention relates to a method for gasifying solid carbonaceous materials wherein the solid carbonaceous materials, in powdered form, are blown in a gas stream towards a bath of molten iron which has been contacted by streams of oxygen. The invention also relates to an apparatus for achieving the method, and to the lances which can be used to discharge the various gas streams.
2. Description of the Prior Art
Prior art methods for gasifying coal wherein the coal is dropped and dissolved directly in a bath of molten iron, and a gas such as oxygen or steam is blown into the bath of molten iron through a lance so that the coal will be gasified by reaction with molten carbon are known, as for example shown in JA-OS Nos. 41604/52, 41605/52 and 41606/52, which applications were laid open for public inspection on Mar. 31, 1977. However, such methods of gasifying coal have numerous drawbacks, some of which are as follows:
I. The coal which is added to the molten iron is caught by the floating slag on the molten iron bath surface and although a part thereof is dissolved in the molten iron by agitation much of the coal will disperse and be lost or else will float with the slag and not be gasified. Thus, the efficiency of coal gasification will be low (not more than 80%), and the content of CO.sub.2 in the produced gas will be high (not below 5 to 6%). An effective gasification will not be obtained.
II. The sulfur in the above-mentioned floating coal will react directly with the added oxygen to produce SO.sub.x and therefore the sulfur which is not contained in the produced gas will be lost.
III. Since the locations of impingement with the molten iron bath of the coal and the blown oxygen or steam are different, an extremely high temperature hot spot will be formed on surface of the molten iron, and therefore a significant loss of molten iron by the evaporation will result. A large amount of combustible metal iron containing microgranules of carbon will then be contained in the produced gas, and the dust treatment thereof will be dangerous. Further, the total amount of molten iron will be increased by the slight amount of iron contained in the adder coal but, depending on the kind of coal used, loss of molten iron by the evaporation will be larger than the above-mentioned increase and thus control of the operation will be difficult.
(IV). There is no way to keep the amount of produced slag constant. Since the amount of slag greatly influences the desulfurization and the efficiency of utilization of coal, it is important to the gasification of the coal to keep the amount of slag constant.
An object of the present invention is to provide a method of gasifying solid carbonaceous materials wherein such defects as mentioned above are eliminated.
Another object of the present invention is to provide an apparatus for gasifying solid carbonaceous materials wherein the efficiency of utilization of the solid carbonaceous materials is high and the content of impurities in the produced gas is very low.
A further another object of the present invention is to provide a non-submerged, top-blowing lance which can achieve the above-mentioned gasification efficiently.